Plastic bottles can be formed from plastic film. One or more webs of the plastic film are unrolled from spools, and are folded and seamed together to form structures known as a preforms. Each preform corresponds to an individual bottle, and has a generally flat shape defined by the flat panels of plastic film. A fitment may be installed in the neck of the preform to provide a spout. The preform is then placed inside a blow-molding cavity that has the size and shape of the bottle, and is expanded under fluid pressure inside the cavity. This deflects the plastic film into the shape of the bottle.